Ewles, Linda
Scutari Press, 1995
Buku Referensi
Rorden, Judith Waring
W.B. Saunders, 1987
Buku Teks SO
Dadzie, Stella
National Institute of Adult Continuing Education, 1993
Buku Teks
Jacobsen, Kathyn
Jones & Bartlett Learning, 2012
Buku Teks
Jacobsen, Kathryn H.
Jones & Bartlett Learning, 2017
Buku Teks SO